Aromatic fluorine-containing organotin compounds and anti-tumour composition

This invention relates to novel aromatic fluorine-containing organotin compounds and to anti-tumour compositions containing said compounds.

The substitution of hydrogen for fluorine substantially influences the biological activity of organic molecules (J. T. Welch, Tetrahedron, 43 (1987), 3123).

Fluorine (Van der Waals radius: 1.35 Å) resembles hydrogen (Van der Waals radius: 1.20 Å) but, because of the strength of the C-F bond, the fluorine substituent is very resistant to metabolic transformations. The very high electronegativity of fluorine, however, makes it quite different from hydrogen: its presence strongly affects the electronic distribution in the molecule, i.e. its dipole moment, the basicity, acidity or reactivity of neighbouring groups, etc.

We have already synthesized several fluorine-containing organotin compounds, of which the antitumour activity was screened against two human tumour cell lines, MCF-7, a mammary tumour, and WiDR, a colon carcinoma.

The di-n-butyltin monofluorobenzoates {(4-F-C 6 H 4 CO 2 SnBu 2 ) 2 O} 2 and (4-F-C 6 H 4 CO 2 ) 2 SnBu 2 (see M. Gielen, A. El Khloufi, M. Biesemans and R. Willem, Appl. Organomet. Chem., 7 (1933), 119-125) are characterized by ID 50 values of 81 and 360, and 90 and 309 ng/ml, respectively, comparable to those observed for etoposide. Of the corresponding difluorobenzoates (see M. Gielen, M. Biesemans, A. El Khloufi, J. Meunier-Piret, F. Kayser and R. Willem, J. Fluorine Chem., 64 (1993), 279-291), the 2,3-difluorobenzoates {(2,3-F 2 C 6 H 3 CO 2 SnBu 2 ) 2 O} 2 and (2,3-F 2 C 6 H 3 CO 2 ) 2 SnBu 2 , exhibit for instance ID 50 values of 9 and 120, and 23 and 283 ng/ml, respectively. This clearly shows that, at least against MCF-7, the activity is enhanced when the number of fluorine atoms of the benzoate moiety is increased. These activities are comparable to mitomycin C. The ID 50 values of corresponding tri- and tetrafluorobenzoates, {(2,3,6-F 3 C 6 H 3 CO 2 SnBu 2 ) 2 O} 2 and {(2,3,4,5-F 4 C 6 HCO 2 SnBu 2 ) 2 O} 2 , are of the same order of magnitude: 13 and 200, and 35 and 250 ng/ml, respectively (see M. Gielen, A. El Khloufi, D. de Vos, H. J. Kolker, J. H. M. Schellens and R. Willem, Bull. Soc. Chim. Belg., 102 (1993), 761-764).

Di-n-butyltintetrafluorophthalate, F 4 C 6 -1,2-(CO 2 ) 2 SnB 2 , (see M. Gielen, M. Bou alam, A. Meriem, B. Mahieu, M. Biesemans and R. Willem, Heteroatom Chem., 3 (1992), 449-452) is characterized by very low ID 50 values, especially against WiDr, viz. 51 and 68 ng/ml.

The di-n-butyltin 2-fluorocinnamates and 4-fluorophenylacetates, {(2-F-C 6 H 4 CH═CHC 2 SnBu 2 ) 2 O} 2 and {(4-F-C 6 H 4 CH 2 CO 2 SnBu 2 ) 2 O} 2 (see M. Gielen, A. El Khloufi, M. Biesemans, F. Kayser and R. Willera, Appl. Organomet. Chem., 7 (1993), 201-206) have comparable activities, i.e. ID 50 values of 28 and 368, and 38 and 268 ng/ml.

The present invention provides novel aromatic fluorine-containing organotin compounds of the formula {(F 5 C 6 RCO 2 SnBu 2 ) 2 O} 2 or {(F 5 C 6 RCO 2 SnBu) 2 } wherein R is CH 2 , CH═CH or a single bond between the phenyl ring and the CO 2 group, and Bu is a butyl group.

This invention also provides anti-tumour compositions, containing as an active ingredient one or more aromatic fluorine-containing organotin compounds as defined above, and a pharmaceutically acceptable carrier.

The present compounds show a markedly better solubility in polar solvents, such as ethanol, than the above discussed tested compounds; the solubility of the present compounds in ethanol is about 10 times higher than that of the known compounds (about 50 mg/ml). Furthermore, the present compounds show activities against a broad spectrum of tumours, as appears from the experimental part disclosed hereinafter.

Syntheses and purifications

The compounds 1 to 3 of the general formula {F 5 C 6 CO 2 SnBu 2 ) 2 O} 2 , {(F 5 C 6 CH 2 CO 2 SnBu 2 ) 2 O} 2 and {(F 5 C 6 CH═CHCO 2 SnBu 2 ) 2 O} 2 , were synthesized from the corresponding organic acid and di-n-butyltin oxide in a 1:1 molar ratio, and {(F 5 C 6 CH 2 CO 2 ) 2 SnBu 2 }, 4, was synthesized employing a 2:1 molar ratio, using the following procedure: The appropriate acid was dissolved in a 4:1 mixture of toluene and ethanol. The reacting mixture was refluxed for 4 to 6 h. The ternary azeotrope, water/ethanol/toluene, followed by the binary, azeotrope ethanol/toluene, were distilled off with a Dean-Stark funnel up to 50% reduction of the initial volume. The solvents were evaporated under reduced pressure. The solid or oil obtained was purified by recrystallization in appropriate solvents.

The following compounds were prepared:

{(F 5 C 6 CO 2 SnBu 2 ) 2 O}) 2 , compound 1

Recrystallized from ethanol/petroleum ether; mp: 151°-153° C., yield: 94%; M ossbauer parameters (in mm/s): QS: 3.68, IS: 1.42, Γ 1 & Γ 2 :1.10 & 0.98; 1 H NMR (CDCl 3 ): α& β-CH 2 : m, 1.46-1.78; γ-CH 2 ; tq, 1.34 [7, 7] and tq: 1,51 [7,7]; CH 3 ;t, 0.87 [7] and t: 0.89 [7]; 13 C NMR (CDCl 3 ): C-1: td, 111.8 [4, 19]; C-2 & C-6: bd, 141.8 [253]; C-3 & C-5: bd, 137.8 [248]; C-4: bd, 144.2 [264]; CO; 164.3; α-C: 28.7 [bs] and 29.8 [bs]; β-C: 27.0 [ 2 J( 13 C- 119/117 Sn): 35] and 27.3 [ 2 J( 13 C- 119/117 Sn): 35]; γ-C: 26.6 [ 3 J( 13 C- 119/117 Sn): 121] and 26.7 [ 3 J( 13 C- 119/117 Sn); 123]; CH 3 13.2 and 13.3; 19 F NMR (CFCl 3 ): F-2 & F-6: dddd,-141.4 [ n J( 19 F-- 19 F): 21, 3, 2,-8]; F-3 & F-5: dddd, -161.2 [ n J( 19 F-- 19 F): 21, 21, 3,-8]; F-4: t, -152.1 [ 3 J( 19 F-- 19 F): 21]; 119 Sn NMR (CDCl 3 ):-189,5,-190.6 [ 2 J( 119 Sn-O- 117/119 Sn): 126]

{(F 5 C 6 CH 2 CO 2 SnBu 2 ) 2 O} 2 , compound 2

Recrystallized from ethanol/petroleum ether; mp: 76°-77° C., yield; 85%; M ossbauer parameters (in mm/s): QS: 3.39, IS: 1.29, Γ 1 & Γ 2 : 0.96 & 0.99; 1 H NMR (CDCl 3 ): CH 2 CO: S, 3.56; α- & β-CH 2 ; m, 1.44-1.54; γ-CH 2 ; tq 1.27 [7, 7] and tq: 1,29 [7,7]; CH 3 ; t, 0.86 [7] and t: 0.89 [7]; 13 C NMR (CDCl 3 ): C-1; dt, 109.9 [17, 4]; C-2 & C-6: bd: 145.3 [247]; C-3 & C-5: bd: 137.4 [253]; C-4; bd; 140.3 [249]; CH 2 CO: 29.6; CO: 173.9; α-C: 29.5 [bs] and 29.1 [bs]; β-C: 27.2 [ 2 J( 13 C- 119/117 Sn): 32] and 27.6 [ 2 J( 13 C- 119/117 Sn): 37]; γ-C: 26.6 [ 3 J( 13 C- 119/117 Sn): 125] and 26.8 [b]; CH 3 : 13.2 and 13.3; 9 F NMR (CFCl 3 ): F-2 & F-6: dddd,-143.4 [ n J( 19 F-- 19 F): 21, 3, 2,-9]; F-3 & F-5: bs ,-163.3; F-4: bs,-156.8; 119 Sn NMR (CDCl 3 ):-204.6,-209.3 [ 2 J( 119 Sn-O- 117/119 Sn): 121]

{(F 5 C 6 CH═CHCO 2 SnBu 2 ) 2 O} 2 , compound 3

Recrystallized from ethanol/petroleum ether; mp: 110°-112° C., yield: 93%; M ossbauer parameters (in mm/s): QS: 3.53, IS: 1.34, Γ 1 & Γ 2 : 0.98 & 0.99; 1 H NMR (CDCl 3 ): α-CH: d, 6.70 [16]; β-CH: d, 7.52 [16]; α- & β-CH 2 ; m, 1.64-1.75; γ-CH 2 ; tq, 1.37 [7, 7] and tq: 1,43 [7,7]; CH 3 ; t, 0.86 [7] and t: 0.89 [7]; 13 C NMR (CDCl 3 ): C-1: td, 110.4 [4, 14]; C-2 & C-6: bd: 145.5 [254]; C-3 & C-5: bd: 137.5 [249]; C-4: bd: 1:37.9 [249]; α-CH: 130.0; β-CH: 126.9; CO: 171.4; α-CH 2 : 29.7 [bs] and 29.7 [bs]; β-CH 2 : 27.4 [ 2 J( 13 C- 119/117 Sn): 36] and 27.7 [ 2 J( 13 C- 119/117 Sn); 36]; γ-CH 2 : 26.6 [ 3 J( 13 C- 119/117 Sn): 121] and 26.8 [ 3 J( 13 C- 119/117 Sn); 125]; CH 3 : 13.2 and 13.3; 19 F NMR (CFCl 3 ): F-2 & F-6: dddd,-140.4 [ n J( 19 -F-- 19 F): 21,3, 1, -8]; F-3 & F-5: dddd,-162.7 [21, 21,3,-8]; F-4: t,-152.9 [21]; 119 Sn NMR (CDCl 3 ): -206.6, -215.5 [ 2 J( 119 Sn-O- 117/119 Sn): 113]

{(F 5 C 6 CH 2 CO 2 ) 2 SnBu 2 }, compound 4

Recrystallized from ethanol/hexane; mp: 125°-126° C., yield: 90%; M ossbauer parameters (in mm/s): QS: 3.85, IS: 1.51, Γ 1 & Γ 2 : 0.99 & 0.89; 1 H NMR (CDCl 3 ): CH 2 CO: s, 3.70; α- & β-CH 2 ; m, 0.58-1.72; γ-CH 2 ; tq, 1.34 [7, 7]; CH 3 ; t, 0.88 [7]; 13 C NMR (CDCl 3 ): C-1: td, 108.7 [3, 18]; C-2 & C-6: bd: 145.3 [248]; C-3 & C-5: bd: 137.5 [253]; C-4: bd: 140.6 [253]; CH 2 CO: 27.7; CO: 178.1; α-C; 25.6 [ 1 J( 13 C- 119/1117 Sn): 561/536]; β-C: 26.4 [ 2 J( 13 C- 119/117 Sn): 35]; γ-C; 26.2 [ 3 J( 13 C- 119/117 Sn): 95]; CH 3 : 13.3; 19 F NMR (CFCl 3 ): F-2 & F-6: dddd, -143.1 [ n J( 19 F-- 19 F): 21, 3, 1,-8]; F-3 & F-5: dddd,-162.9 [21, 21, 3,-8]; F-4: t, -156.1 [21]; 119 Sn NMR (CDCl 3 ):-131.3

The above compounds were tested in vitro against the following human tumour cell lines

MCF-7 breast cancer

EVSA-T breast cancer

WIDR colon cancer

IGROV ovarian cancer

M19 MEL melanoma

A498 renal cancer

The tests were carried out according to the method of Y. P. Kepers, P. E. Pizao, G. J. Peters, J. Van Ark-Otte, B. Winograd, H. M. Pinedo, Comparison of the sulforhodamine B protein and tetrazolium (MTT) assays for in vitro chemosensitivity testing. Eur. J. Cancer 27: 897-900; 1991.

The ID 50 values in mg/ml for the above for compounds and for two known compounds (carboplatin and cisplatin) were determined according to the above mentioned procedure. ID 50 is the amount which inhibits 50% of the cell growth. The results are shown in the following table.

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ID.sub.50 values in mg/ml

Compounds

MCF-7 EVSAT WiDr IGROV M19 A498

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1 44 39 214 53 86 76

2 55 43 275 60 114 105

3 32 37 234 41 66 135

4 10 19 145 20 36 51

Carboplatin

5500 1100 1500 780 5300 3500

Cisplatin

800 1200 650 79 530 1200

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From the above results it can be seen that the present organotin compounds exhibit excellent ID 50 values which are considerably lower than the ID 50 values of the known compounds which were tested for comparative purposes.